A sub fleet of about 50+ deep water subs is more valuable than squadrons of fifth gen fighters and dozens of frigates.
Maneuvering Hypersonic missiles will change warfare in the future and subs are UNDERWATER. Jet fighters and frigates are on the surface.
Subs are vulnerable by themselves and without a surface fleet to protect them.
It’s pretty easy to locate a submarine over time based on intercepting radio communications and then sending sub hunter patrol planes to pinpoint location.
After the sub has been narrowed to a general area, it’s over for the submarine. Either they surface or get crushed like a soda can under the sea.
Only reason submarines truly exist this day and age is to project second strike nuclear capability for a country and to ward off adversary submarines from carrier fleet.
If an enemy doesn’t know exact location of all of his adversary’s nuclear weapon equipped submarines then he cannot order nuclear wave strike without risking the own homeland to retaliation strike.
Personally Iran should eliminate Ghadir design and focus on building unmanned subs in the tonnage range of Ghadir and Fateh.
Manned subs below 1000 tons is inefficient use of resources.
https://www.quora.com/How-deep-must-you-go-in-a-submarine-to-avoid-a-bad-storm-on-the-sea
My guess with no storms, the Fetah could patrol the entire Arabian Sea. It is large enough for range and could support a crew for weeks. The main problem is storms.
The issue of depth would be for submarine warfare, less so for warfare against surface vessels.
Actually depth is also used for warfare against surface vessels and detection avoidance.
Hence why Soviet Union used titanium hulls in some submarines to achieve extreme depths.
Much harder for a surface vessel to detect and hit a sub at 1000 meters than at 300 meters.